What Type of Drug is Cefazolin
Cefazolin is a first-generation cephalosporin antibiotic, which is a semi-synthetic beta-lactam antimicrobial agent administered parenterally. 1
Chemical Classification and Structure
- Cefazolin belongs to the cephalosporin class of antibiotics, specifically classified as a first-generation cephalosporin. 1, 2
- It contains a beta-lactam ring structure but has a different molecular configuration than penicillins, with unique R1 side chains that do not match any currently available penicillins. 3, 4
- The chemical structure is the sodium salt of 3-{[(5-methyl-1,3,4-thiadiazol-2-yl)thio]-methyl}-8-oxo-7-[2-(1H-tetrazol-1-yl) acetamido]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid. 1
Mechanism of Action and Antimicrobial Spectrum
- Cefazolin is bactericidal against most gram-positive cocci (including methicillin-susceptible Staphylococcus aureus and Streptococcus species) and many gram-negative bacilli of clinical importance. 2, 4
- It demonstrates greater stability against certain beta-lactamases compared to penicillins, though not all. 4
- The drug is not active against enterococci, Bacteroides fragilis, or Pseudomonas aeruginosa. 2
Clinical Applications
- Cefazolin is the antibiotic of choice for surgical prophylaxis in most procedures, as recommended by major surgical societies including the American Society of Health-Systems Pharmacists, Infectious Diseases Society of America, Surgical Infection Society, and Society for Healthcare Epidemiology of America. 5
- It is specifically recommended for prophylaxis in cardiac surgery, orthopedic surgery, neurosurgery, gastrointestinal procedures, urological procedures, obstetric/gynecologic surgery, and plastic surgery. 5
- The Australian Therapeutic Guidelines state that cefazolin is preferable for most procedures when prophylaxis is needed. 5
Pharmacokinetic Advantages
- Cefazolin has a longer half-life than many other beta-lactams, requiring less frequent dosing. 4
- It achieves high tissue concentrations, including intra-amniotic concentrations, with a tissue penetration ratio of approximately 1.06 (tissue/serum free drug area under the curve). 4, 6
- Each vial contains 48 mg of sodium per 1 gram of cefazolin sodium. 1
Safety Profile in Penicillin Allergy
- Cefazolin demonstrates negligible cross-reactivity with penicillins (0.7-0.8%) because it does not share side chains with any currently available penicillins, making it safe for patients with penicillin allergy, including those with immediate-type reactions. 3, 7
- The Dutch Working Party on Antibiotic Policy (SWAB) provides a strong recommendation with moderate quality evidence that cefazolin can be safely administered to patients with penicillin allergy regardless of severity or timing of the index reaction. 3